Ion mobility sensors and spectrometers having a corona discharge ionization source

Abstract

A chemical sensor comprising a gas detector having first and second printed wiring boards with opposed separated pairs of signal and grounded counter electrodes and processing electronics for processing ionic current signals derived from the signal and counter electrodes. A corona discharge source is provided that produces an ionized air stream containing a chemical that is to be detected. An insulating plate is disposed between the second printed wiring board of the gas detector and the corona discharge source that is used to electrically isolate the electrodes and processing electronics of the gas detector from the corona discharge source. An air flow passage is formed through the corona discharge source, the insulating plate, and the gas detector that allows the ionized air stream generated by the corona discharge source to flow past the signal and counter electrodes, so that the chemical may be detected.

What is claimed is: 
     
       1. An ion mobility sensor comprising: a gas detector comprising: a first printed wiring board having a plurality of signal electrodes;   a second printed wiring board having a plurality of grounded counter electrodes separated from the first printed wiring board; and   processing electronics coupled to the signal and counter electrodes for processing ionic current signals derived therefrom;     a corona discharge source;   an insulating plate disposed between the second printed wiring board of the gas detector and the corona discharge source; and   an air flow passage formed through the corona discharge source, the insulating plate, and the gas detector for permitting an ionized air stream generated by the corona discharge source to flow past the signal and counter electrodes.   
     
     
       2. The sensor of claim 1 wherein the corona discharge source is fabricated on a corona discharge printed wiring board. 
     
     
       3. The sensor of claim 1 wherein the corona discharge source is disposed in an insulator block disposed adjacent to the insulating plate. 
     
     
       4. The sensor of claim 3 wherein the insulator block comprises Teflon material. 
     
     
       5. The sensor of claim 1 wherein the insulating plate comprises an alumina plate. 
     
     
       6. The sensor of claim 1 wherein the first and second printed wiring boards are separated by an insulating spacer. 
     
     
       7. The sensor of claim 6 wherein the insulating spacer comprises Teflon material. 
     
     
       8. The sensor of claim 1 wherein the corona discharge ionization source comprises: a power supply;   a first electrode coupled to the power supply; and   a ground plane coupled to the power supply and disposed adjacent to the first electrode and displaced therefrom by a predetermined distance.   
     
     
       9. The sensor of claim 1 wherein the corona discharge ionization source comprises: a power supply;   a first plurality of electrodes coupled to the power supply; and   a ground plane coupled to the power supply and disposed adjacent to the first plurality of electrodes and displaced therefrom by a predetermined distance.   
     
     
       10. An ion mobility sensor comprising: a gas detector comprising: a plurality of signal electrodes;   a plurality of grounded counter electrodes separated from the first plurality of signal electrodes; and   processing electronics coupled to the signal and counter electrodes for processing ionic current signals derived therefrom;     a corona discharge source;   an insulating plate disposed between the plurality of signal electrodes of the gas detector and the corona discharge source; and   an air flow passage formed through the corona discharge source, the insulating plate, and the gas detector for permitting an ionized air stream generated by the corona discharge source to flow past the signal and counter electrodes.   
     
     
       11. The sensor of claim 10 wherein the corona discharge ionization source comprises: a power supply;   a first electrode coupled to the power supply; and   a ground plane coupled to the power supply and disposed adjacent to the first electrode and displaced therefrom by a predetermined distance.   
     
     
       12. The sensor of claim 10 wherein the corona discharge ionization source comprises: a power supply;   a first plurality of electrodes coupled to the power supply; and   a ground plane coupled to the power supply and disposed adjacent to the first plurality of electrodes and displaced therefrom by a predetermined distance.